Private allocated networks over shared communications infrastructure

ABSTRACT

Methods and systems for implementing private allocated networks in a virtual infrastructure are presented. One method operation creates virtual switches in one or more hosts in the virtual infrastructure. Each port in the virtual switches is associated with a private allocated network (PAN) from a group of possible PANs. In one embodiment, one or more PANs share the same physical media for data transmission. The intranet traffic within each PAN is not visible to nodes that are not connected to the each PAN. In another operation, the method defines addressing mode tables for the intranet traffic within each PAN. The entries in the addressing mode tables define addressing functions for routing the intranet traffic between the virtual switches, and different types of addressing functions are supported by the virtual switches.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No. 12/510,072 (Attorney Docket No. A355), filed Jul. 27, 2009, and entitled “AUTOMATED NETWORK CONFIGURATION OF VIRTUAL MACHINES IN A VIRTUAL LAB ENVIRONMENT”; and U.S. patent application Ser. No. 12/510,135 (Attorney Docket No. A366), filed Jul. 27, 2009, and entitled “MANAGEMENT AND IMPLEMENTATION OF ENCLOSED LOCAL NETWORKS IN A VIRTUAL LAB”, which are incorporated herein by reference.

1. FIELD OF THE INVENTION

The present invention relates to methods and systems for implementing private allocated networks (PAN), and more particularly, methods and systems for implementing isolated PANs that share the same communication physical media.

2. DESCRIPTION OF THE RELATED ART

Virtualization of computer resources generally involves abstracting computer hardware, which essentially isolates operating systems and applications from underlying hardware. Hardware is therefore shared among multiple operating systems and applications wherein each operating system and its corresponding applications are isolated in corresponding virtual machines (VM) and wherein each VM is a complete execution environment. As a result, hardware can be more efficiently utilized.

The virtualization of computer resources sometimes requires the virtualization of networking resources. To create a private network in a virtual infrastructure means that a set of virtual machines have exclusive access to this private network. However, virtual machines can be located in multiple hosts that may be connected to different physical networks. Trying to impose a private network on a distributed environment encompassing multiple physical networks is a complex problem. Further, sending a broadcast message in a private network presents two problems. First, the broadcast may be received by hosts which do not host any VMs in the private network, thus reducing the scalability of the entire distributed system. Second, if hosts are not located on adjacent layer 2 networks, the broadcast may not reach all hosts with VMs in the private network.

Virtual Local Area Networks (VLAN) are sometimes used to implement distributed networks for a set of computing resources that are not connected to one physical network. A VLAN is a group of hosts that communicate as if they were attached to the Broadcast domain, regardless of their physical location. A VLAN has the same attributes as a physical Local Area Network (LAN), but the VLAN allows for end stations to be grouped together even if the end stations an not located on the same network switch. Network reconfiguration can be done through software instead of by physically relocating devices. Routers in VLAN topologies provide broadcast filtering, security, address summarization, and traffic flow management. However, VLANs only offer encapsulation and, by definition, switches may not bridge traffic between VLANs as it would violate the integrity of the VLAN broadcast domain. Further, VLANs are not easily programmable by a centralized virtual infrastructure manager.

SUMMARY

Embodiments of the present invention provide methods and systems for implementing private allocated networks in a virtual infrastructure are presented. One method operation creates virtual switches in one or more hosts in the virtual infrastructure. Each port in the virtual switches is associated with a private allocated network (PAN) from a group of possible PANs. The intranet traffic within each PAN is not visible to nodes that are not connected to the each PAN. In another operation, the method defines addressing mode tables for the intranet traffic within each PAN. The entries in the addressing mode tables define addressing functions for routing the intranet traffic between the virtual switches, and types of addressing functions an supported by the virtual switches.

It should be appreciated that the present invention can be implemented in numerous ways, such as a process, an apparatus, a system, a device or a method on a computer readable medium. Several inventive embodiments of the present invention are described below.

In one embodiment, a method includes an operation for sending a packet from a virtual machine to a virtual switch in a host where the virtual machine is executing. The packet is sent from a network interface in the virtual machine connected to a PAN. Further, the method checks an addressing mode table in the virtual switch to determine an addressing function corresponding to a destination node for the packet. The addressing function is defined for routing intranet PAN traffic between virtual switches connected to the PAN, where different types of addressing functions are supported by each virtual switch. Another method operation sends the packet to the destination using the determined addressing function.

In another embodiment, a virtual switch in a first host for implementing private allocated networks in a virtual infrastructure is defined. The virtual switch includes a first group of ports, a second group of ports, and an addressing mode table. The first group of ports is associated with a first PAN, and the second group of ports is associated with a second PAN. The first and the second PAN share the same physical media for data transmission, and the intranet traffic within the first PAN is not visible to nodes that are not directly connected to the first PAN. The addressing mode table is characterized for the intranet traffic within the first PAN. An entry in the addressing mode table defines an addressing function for routing intranet traffic originated at the first group of ports, where layer 2 address translation is used for intranet traffic from the first group of ports to a virtual machine in a second host connected to the same physical media. Layer 3 encapsulation is used for intranet traffic from the first group of ports to a virtual machine in a third host not connected to the same physical media.

In yet another embodiment, a system for network communications in a virtual infrastructure includes one or more physical networks and a plurality of hosts connected to the physical networks. Each host includes a virtual switch and addressing mode tables. Each port in the virtual switch is associated with one of a plurality of PANs. Nodes in each PAN have the same network address associated with the each PAN, and each port can be associated with any of the PANs. Further, the intranet PAN traffic between two hosts on different physical networks travels through the two different physical networks. The addressing mode tables are defined for each PAN, where an entry in the addressing mode table defines an addressing function for routing the intranet PAN traffic between the plurality of hosts. Different types of addressing functions are supported by the plurality of hosts.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a remote desktop environment including a virtual infrastructure controller, according to one embodiment.

FIG. 2 depicts one embodiment of the host architecture for instantiating Virtual Machines (VM) with multiple Virtual Network Interface Cards (VNIC).

FIG. 3 illustrates the implementation of Private Allocated Networks (PAN) in a virtual infrastructure, according to one embodiment.

FIG. 4 illustrates the transmission of PAN packets between hosts connected to the same physical network, according to one embodiment.

FIG. 5 illustrates the transmission of PAN packets between physical networks and within a host, in accordance with one embodiment.

FIG. 6 depicts the transmission of broadcast packets within a PAN, according to one embodiment.

FIGS. 7A-7B present two embodiments of network addressing mode tables.

FIG. 8 illustrates the process of migrating a VM to a host which has no support for the PAN used by the migrating VM, according to one embodiment.

FIGS. 9A-9B illustrate the implementation of PANs in multiple layers, according to one embodiment.

FIG. 10 shows the process flow for implementing private allocated networks in a virtual infrastructure in accordance with one embodiment of the invention.

FIG. 11 is a simplified schematic diagram of a computer system for implementing embodiments of the present invention.

DETAILED DESCRIPTION

FIG. 1 depicts a remote desktop environment including a virtual infrastructure controller, according to one embodiment. The environment depicted in FIG. 1 includes enterprise servers 102 a-102 b, also referred to herein as hosts, that provide virtual desktop services to remote users 130 a-130 d. Although embodiments are described within a virtual desktop system and virtual machines (VM), the embodiments presented can be used in environments where several servers are used to support processes which can be hosted by any of the servers. Some embodiments below are described with respect to VMs, but the same principles apply to processes running on a multi-host environment.

The architecture of a virtualized computer system is shown in FIG. 1 with some components omitted for simplification purposes. The virtualized computer system includes VMs 104 a-104 n, and virtual infrastructure 108. Among other things, virtual infrastructure 108 manages the assignment of VMs 104 a-104 n to remote users. As shown in FIG. 1, each VM includes a Guest Operating System (GOS) supporting applications running on the GOS. Virtual infrastructure layer 108 also includes Virtual Switch 106 that provides network connectivity services to VMs 104 a-104 n. Virtual Infrastructure Controller 132 manages the operation of the hosts in the infrastructure, which includes allocating VMs to hosts, migrating VMs between hosts, configuring networks, etc.

As further shown in FIG. 1, remote users 130 a-130 d utilize devices 122, 124, 126 and 128, respectively, which act as clients in the remote desktop environment. Devices 122, 124, 126 and 128 provide display presentation and input/output capabilities associated with VMs 104 a-104 n. The devices include Personal Computers (PC) 122 and 128, laptop 124, and a Personal Digital Assistant (PDA) (mobile phone 126). As further shown in FIG. 1, the devices can communicate with the hosts over the same private network 114 as the hosts, or they can communicate with the hosts remotely via network 112.

FIG. 2 depicts one embodiment of the host architecture for instantiating VMs with multiple Virtual Network Interface Cards (VNIC). Hypervisor 204, also referred to as virtual infrastructure layer, manages the assignment of VMs 206 in host 202 to remote users. VM 206 includes Guest Operating System (GOS) 208 and multiple VNICs 210. Each VNIC 210 is connected to a virtual switch (VSwitch) 212 that provides network switch functionality for the network interfaces. VSwitches 212 are connected to a physical NIC device in the host to connect the VMs to network 216. Each of the VNICs and VSwitches are independent, thus a VM can connect to several networks via several VNICs that connect to one or more physical NIC devices 214. In another embodiment, each VSwitch 212 is connected to a different physical NIC device, thus each VSwitch 212 provides connectivity for networks implemented on the corresponding network attached to the physical NIC device. For example, in the embodiment illustrated in FIG. 2, physical network 216 carries traffic for two different networks, Network 1 and Network 4. Network 1 and Network 4 are two network overlays operating on the same physical network 216. VSwitch 212 assigns a set of ports to Network 1 and a different set of ports to Network 4, where each set of ports supports Media Access Control (MAC) addressing for the corresponding network. Thus, packets from Network 1 coexist with packets from Network 4 on the same transmission media.

The network overlays are configured to have separate Layer 2 (Ethernet) and Layer 3 (Internet Protocol) addressing from the underlying physical infrastructure, allowing a physical network or a PAN to have different subnet masks, gateways, and IP address pools from the underlying physical network. Further, the PANs may be connected to a virtual router in order to provide connectivity to the underlying physical network infrastructure or another PAN via a gateway or default router.

FIG. 3 illustrates the implementation of Private Allocated Networks in a virtual infrastructure, according to one embodiment. Virtual Infrastructure Controller 302 manages a virtual infrastructure with hosts 1-5 304 a-304 e. Physical Networks PN1 and PN2, together with router 308, enable the hosts to communicate and VMs A-R execute on hosts 1-5. The administrator of this environment wishes to create multiple private networks, also referred to herein as Private Allocated Networks (PAN) or network overlays, which are independent from each other. A PAN defines a layer 2 broadcast domain. In case of an IP PAN network, all the nodes in the PAN have the same subnet network address and a different nodal address. Typically, each PAN is under the control of a different administrator. For example, each business unit in a large corporation may have its own network, or networks are allocated to different functions within a company, such as having a network for lab testing completely isolated from networks that nm mission-critical operations such as order processing. Having independent networks means that the addressing schemes within each network can not affect the operation of other networks, and that the networks are protected from outside entities that are not properly authorized to establish a network connection. Additionally, each administrator must be free to define the addressing scheme used in the networks under the control of the administrator, independently of how other administrators configure their networks. Networking layer 2 and layer 3 addresses can be the same in different VMs connected to different PANs, but the overlap must not affect the normal operation of the VMs, the network, nor the virtual infrastructure. Having independent networks also means isolation of the physical infrastructure from the view of each VM. In other PAN scenarios, an administrator breaks down a large physical network into a set of smaller networks, or combines small subnets into a large network without having to change the configurations and connections of the network equipment.

In the virtual infrastructure environment of FIG. 3 all hosts run virtualization software, which is centrally managed. Additionally, all the nodes are well behaved and controlled. The central management allows the implementation of solutions that may be harder to implement on open networking environments where the nodes are not controlled by a central entity. However, the person skilled in the art will readily appreciate that many of the principles described herein can also be used in open networking environments with little or no modification.

There are three basic tools used to implement overlay networks: filtering, encapsulation or address translation, and forwarding. The filtering function assigns all traffic to a given overlay or set of overlays upon ingress, and prevents traffic from passing between segments which must be isolated from one another. The encapsulation function prevents unintended routing of packets by the physical switching and routing equipment when there is overlapping duplicate addresses within separate isolated segments. Further, the encapsulation function tunnels traffic within a given logical segment across disparate physical segments. The forwarding function provides feedback to the core forwarding engine which may make implicit assumptions based on whether a suitable local unicast destination is available or not.

Embodiments of the invention add optimization to the virtual infrastructure networking stack to enable the virtual infrastructure to:

-   -   Protect the physical network from overlapping MAC and IP         addresses in different administration domains.     -   Divide a large shared physical network into smaller isolated         networks to provide multi-tenancy capabilities. This means         preventing traffic from leaking between isolated networks,         restricting broadcast domains to only the set of physical         switches actually servicing a given isolated network, and         enabling the deployment of a single large layer 2 network with         no spanning tree running at the physical access layer, or with         optimized spanning tree compared to traditional networks because         there is no need for loops built into the network as redundancy         can be handled at the edges by the hypervisors, and there is no         need to run spanning tree over multiple VLANs.     -   Aggregate a collection of separate subnets into a larger logical         network, which can be subdivided to combine multi-tenancy with         availability zones. This aggregation allows the traditional use         of spanning tree for redundancy since each subnet is its own         spanning tree domain. As a result, logical broadcast domains are         stretched beyond physical broadcast boundaries (subnets).     -   Support elastic overlay networks that can “stretch” or         “contract” across L2 and L3 boundaries.     -   Optionally, allows placement of VMs in the virtual         infrastructure so as to improve performance. For example,         Distributed Resource Scheduling (DRS) or other placement         mechanisms can be used to physically collocate VMs in the same         logical private network. As a result, bisectional bandwidth         becomes less critical to the performance of the overall network,         allowing overcommit (or at least less overprovision). In         addition, more aggressive power saving mechanisms can be         implemented for idle switches, and the number of hosts sharing         any one group membership table can be limited.

Virtual infrastructure controller (VIC) 302 allocates unique MAC addresses to each VM's NIC for use in Physical Networks. The PAN administrator allocates MAC addresses to the VMs for internal use within the PAN, but ultimately the PAN packets may need to use a physical network and when the PAN packets travel in the physical network the PAN packets must have unique addresses to avoid delivery problems. VIC 302 also associates VMs with the corresponding PANs and pushes addressing mode tables to the hosts of the virtual infrastructure. The addressing mode tables, also referred to as translation tables or lookup tables, are described in more detail below in reference to FIGS. 7A-7B. In another embodiment, the addressing mode tables are built by each of the hosts without the cooperation from VIC 302. Hosts 304 a-304 e associate individually outgoing frames with one of the PANs and decide which PAN corresponds to each received frame. Additionally, the hosts enforce the isolation between PANs and maintain the addressing mode tables.

The approach to implement PANs over one or more physical networks is elastic as embodiments of the invention do not rely on a single approach or method for transferring packets. Different encapsulation and translation mechanisms are utilized, including leaving a packet unchanged when the destination of the packet is in the same virtual switch as the VM transmitting the packet. Further, embodiments of the invention are compatible with other networking aggregation mechanisms, such as VLANs, because all the operations on packets are performed at the hosts. While PAN packets are travelling on physical networks, the PAN packets behave as regular network packets. Physical network switches and routers are not aware of the network overlays, and there is no need of complex management of switches and routers, which may be geographically dispersed or under the management control of multiple entities.

Referring back to FIG. 3, physical networks PN1 312 and PN2 314 support connections to hosts 304 a-304 e and VIC 302. On top of this physical network infrastructure six different PANs N1-N6 have been created for the VMs in the infrastructure. For example, PAN N2 includes VMs J in host 1, A and B in host 2, and E in host 4. The VMs are connected to VSwitches 306 a-306 e, as previously described in FIG. 2. Although FIG. 3 shows one VSwitch per host, there can be more than one VSwitch instantiated within a host to perform the VSwitch functionality. Each VSwitch assigns ports to one or more PANs implemented in the host. For example, VSwitch 306 b has assigned two ports to PAN N2 and four ports to PAN N5. It should be noted, that hosts need not implement all the PANs in the virtual infrastructure, but only the PANs that have VMs in the host.

VIC 302 allocates PANs to VMs and the ports in the VSwitches where the VMs connect to the PAN. Distributed Virtual Switch 310 in VIC 302 is a symbolic representation of these assignments, where the master Distributed Virtual Switch 310 has an allocation for all VMs. Each port in Distributed Virtual Switch 310 corresponds to a port in a host VSwitch, as shown by some of the arrows coming out of Distributed Virtual Switch 310 (not all ports in Distributed Virtual Switch 310 and arrows are shown for clarity).

It should be noted that one advantage of a virtual infrastructure is that there is no need to artificially constrain broadcasts, mainly used when nodes do not know about each other. In the architecture shown in FIG. 3, all the nodes can get information about other nodes because of the virtual infrastructure layer. For example, a VM can get the Ethernet address of another VM from the virtual infrastructure that knows the addresses of all the VMs. Nevertheless, standard networking methods are also available, such as using Address Resolution Protocol (ARP). However, other embodiments follow a different approach where the virtual infrastructure handles all cases of broadcast, and the virtual infrastructure avoids intruding into the guest OS.

FIG. 4 illustrates the transmission of PAN packets between hosts connected to the same physical network, according to one embodiment. The system in FIG. 4 is the same system as the one of FIG. 3, but some elements have been omitted for clarity. When a packet is transmitted from VM H to VM I using PAN N1, VSwitch 306 a receives the packet in the port attached to VM H. VSwitch 306 a examines the layer 2 destination address and determines that the packet is destined to node 1, also in PAN N1 and in the same virtual switch. Because the destination is local within the VSwitch, the packet is delivered 402 by VSwitch 306 a to the port attached to VM I without changing any data in the packet. Network based applications and services which parse beyond the Ethernet header should not be impacted because there are not any additional data fields or headers added to the packet, which is the case when encapsulation is used.

A second scenario includes sending an IP packet from VM M in host 304 c to VM P in host 304 e. Since the destination is in a different host, the packet must travel through the physical network. As previously discussed, the Ethernet addresses in different PANs may be controlled by different administrators, each with complete freedom to determine how to assign MAC addresses to VMs. This may cause the duplication of MAC addresses, and since a VM's MAC address may not be unique, there must be a mechanism in place to avoid wrongful delivery of packets. This is avoided by assigning a unique MAC address to each VM, which we refer to as the “external” MAC address, and the unique MAC address is used on the physical networks. The MAC addresses used within each PAN are referred to as the “internal” MAC addresses because the MAC addresses are only valid within the corresponding PAN. This assignment can be performed by VIC 302, as seen in FIG. 3.

As a result, the packet sent by VM M is received by VSwitch 306 c, which determines that the destination is in the same PAN and in a different host. Since the remote host 304 a is in the same physical network PN2, the packet can be sent using MAC address translation. VSwitch 306 c changes the destination MAC address to VM P's external MAC address and then sends the packet 404 via network PN2 to VSwitch 306, where the process is reversed. VSwitch 306 e recognizes that the packet came from the physical network and that it is destined to VM P's external address, and VSwitch 306 e then changes the destination address in the packet back to the original “internal” address for VM P in PAN N1. A similar process takes place with the source MAC addresses to use external addresses in the physical network and internal addresses within the PAN.

Network based applications and services which parse beyond the Ethernet header should not be impacted in this case either, since additional data fields are not added to the packet. It should be noted that if the host participates in protocols which embed the MAC in the payload, such as Address Resolution Protocol (ARP), then a translation handler for each relevant protocol must be implemented on the host.

Other embodiments may use different ways of sending packets between hosts. For example, the packet may be sent from VSwitch 306 c to VSwitch 306 e using packet encapsulation. This method may require packet fragmentation because of the added data fields, as well as additional processing to add and deleted the packet extra fields. The important thing to keep in mind is the flexibility and ability to customize how packets are send within a PAN. More details are given below on how customization takes place by using Addressing Mode Tables described in reference to FIGS. 7A-7B.

FIG. 5 illustrates the transmission of PAN packets between physical networks and within a host, in accordance with one embodiment. When VM J in PAN N2 sends a packet to VM B also in PAN2, the packet must travel to a different host located on a remote physical network PN1. In one embodiment, IP encapsulation is used by adding Ethernet and IP headers to the Ethernet packet. Because the packet's destination is VM B, VSwitch 306 determines that the packet needs to be delivered to host 304 b. The added IP header includes the IP address of host 304 b as well as other information regarding the encapsulation of the packet, such as reserved bits. In one embodiment, encapsulated packets include metadata (such as explicit PAN identification). In another embodiment, metadata is not used, and PAN identification is implicit in the encapsulation address. In both embodiments only hosts which implement the PAN will see the traffic for the PAN.

The encapsulated IP packet 502 is sent to router 308 (the added Ethernet header has router 308's Ethernet address for destination), which forwards the packet to host 304 b. VSwitch 306 b determines that the packet is encapsulated, removes the encapsulation headers, and determines delivery for VM B by examining the Ethernet address in the packet (VM B's external Ethernet address). It should be noted that there may be a case when two hosts implement the same PAN, where the two hosts do not share a connection to a physical network and where there is no router on the network that can be used to send packets between the two hosts. In this case, a way to communicate the hosts must be found, such as using an intermediary host with connectivity to both hosts. In this case, a packet originating in one host is sent to the intermediary host, which forwards the packet to the destination host. As previously discussed, translation or encapsulation can be used at each leg of the communication. In one embodiment, the intermediary host implements the same PAN as the other two hosts, but in another embodiment, the intermediary does not implement the same PAN and merely acts as a special router controlled by the virtual infrastructure.

As previously discussed, PANs are implemented as isolated networks which do not require knowledge of the existence of other PANs. However, one administrator can configure several PANs and enable communication among them. In this case, nodes in one of the PANs are aware of other nodes in different PANs and use standard networking protocols to communicate with these nodes. For example, in the case where VM R in PAN N4 sends a packet to VM P in PAN N1, the virtual infrastructure is able to deliver this packet by using a virtual router to facilitate the connection between PANs. In different embodiments, the virtual router can be located in different systems, such as in the source host, in the destination host, or somewhere else on the network. In the example shown in FIG. 5, virtual router 508 is located inside host 304 e.

VSwitch 306 e sends the packet 504 received from VM R to virtual router 508, which then forwards the packet 506 back to VSwitch 306 e for delivery to VM P. Since the packet does not have to travel on a physical network, there is no need for translation or encapsulation. In one embodiment, the virtual router is implemented as a VM which can perform the usual router functions such as encapsulation, decapsulation, and translation. In the case that inter-PAN traffic, that is traffic between PANs, requires that a packet traverses at least one physical network, encapsulation or translation can be used as previously described. We will refer to intranet PAN traffic herein as traffic whose source and destination are in the same PAN, which is the same as saying that an internet PAN packet has source and destination layer 3 addresses from the same network (the PAN network).

FIG. 6 depicts the transmission of broadcast packets within a PAN, according to one embodiment. Different types of broadcasts are illustrated in FIG. 6. The first type is a broadcast from VM B in PAN N2. The broadcast must reach all the nodes in PAN N2, which are executing in hosts 304 a, 304 b, and 304 d. Since B resides in host 304 b, all VMs in host 304 b receive the broadcast from VSwitch 306 b. The nodes outside host 304 b are reached via multicast. To avoid flooding the physical networks, all the broadcasts within a PAN are delivered via multicasts. That is, all the hosts hosting a particular PAN are registered for a common multicast. This way, VSwitch 306 d receives the multicast from VM B and delivers B's broadcast to all nodes in PAN N2 (VM E). Another multicast packet is delivered to VSwitch 306 a (passing through router 308), which delivers B's broadcast to all nodes in PAN N2 (VM J.) It should also be noted that the implementation may choose to optimize this case by only sending the encapsulated multicast since that will be able to be received by hosts on the local network PN1 as well as the remote network PN2.

A second broadcast is sent from VM N, which is connected to VSwitch 306 c in host 304 c. Since all the VMs for N3 are connected to VSwitch 306 c, the virtual switch delivers the broadcast to all the ports configured for PAN N3.

A third broadcast is sent from node H on PAN N1. The hosts implementing PAN N1 are 304 a, 304 c, and 304 e, which are connected to the same physical network PN2. In similar fashion to B's broadcast, the broadcast from H is converted into a multicast that includes all the nodes in PAN N1. This way, the broadcast is transmitted to VSwitches 306 a, 306 c, and 306 e which deliver the broadcast to N1's nodes (I, M, P, and Q).

Therefore, translating all broadcasts to multicast allows to solve the problems where the broadcast ranges too wide on L2, that is the broadcast reaches all the hosts on the physical network causing performance degradation. Additionally, the broadcasts are cut off at the L3 boundary, so broadcasts do not have to reach hosts without VMs belonging to the PAN for the broadcast. A protocol such as Internet Group Management Protocol (IGMP) is used to register the multicast groups. IGMP is a communications protocol used to manage the membership of IP multicast groups. IGMP is used by IP hosts and adjacent multicast routers to establish multicast group memberships.

FIGS. 7A-7B present two embodiments of network addressing mode tables. The addressing mode tables are used to determine how to distribute packets within a PAN. In one embodiment, each entry in the addressing mode table includes a destination key, a function, and an address to use for the destination. In other embodiments, other fields are included to further define the routing of packets or to offer more than one option for routing packets within the PAN. FIG. 7A illustrates the Addressing Mode Table in host 2 304 b (see FIGS. 3-6) for PAN N5. The first entry indicates that the destination is a broadcast, that is, all the nodes in PAN N5. The function associated indicates that delivery of the broadcast is done via a multicast, and the address to use is the IP Multicast address determined for PAN N5.

The next entry corresponds to a unicast address for VM C (Layer 2). Since VM C is in host 2, then the packet can be delivered locally. Thus, the corresponding function is “No modification.” The address to be used is C's unicast address without need for translation or encapsulation. The entry or the unicast L2 address of VM D is similar to the entry for VM C because VM D is also local in host 2.

In another embodiment, the same translation table is used in all the hosts. Since the translation function is only executed when the forwarding mechanism determines that the destination is on another host, the fact that the table contains a translation does not actually mean that the internal traffic is translated.

For unicast F address, the function determines an address translation at level 2 because VM F is in a host that shares the same physical network with host 2. As previously described, L2 address translation can be used to send the packet to VM F and the destination address is VM F's external address, referred to as F′ in FIG. 7A. This is the general case for unicast addresses in the same physical network.

FIG. 7B illustrates the addressing mode table in host 2 for PAN N2. Some entries are similar to those discussed above in reference to FIG. 7A, but a new type of entry appears in FIG. 78 corresponding to the unicast address for VM J. Host 1 where VM is executing is in a different physical network than host 2, therefore IP encapsulation is used to send the packet across, as previously described in FIG. 5 to send a packet from VM J to VM B. The function for this entry specifies IP encapsulation, and the IP address used in the encapsulation header is the IP address of host 1 in PN2.

In one embodiment, the addressing mode tables, also referred to as translation tables or address lookup tables, are centrally managed by the virtual infrastructure controller which downloads them to the different hosts and updates them as changes occur, such as when a VM is migrated to a different host. In another embodiment, the addressing mode tables are managed by each of the hosts, which cooperate with each other to fill in the corresponding information and to do updates as the VMs change status. In yet another embodiment, the different functions for creating and updating the tables are divided between the hosts and the virtual infrastructure controller. For example, the VIC does the initial creating of the tables, while the hosts update the tables as the VM status change over time. It should be noted that in some embodiments, for the case where all the hosts are on the same physical network and only translation is used, VM migrations never require table updates and the tables on each host are identical.

Reverse lookup tables exist in each of the host that perform the inverse function of the addressing mode tables, that is, once a packet arrives, the reverse lookup tables and the corresponding associated reverse logic are used to determine the PAN and final destination of arriving packets.

FIG. 8 illustrates the process of migrating a VM to a host which has no support for the PAN used by the migrating VM, according to one embodiment. One aspect of virtualization is the ability to live migrate workload transparently from one host computer of a virtualized computer system to another, where live migration is sometimes referred to as VMotion. With VMotion, work loads can be dynamically balanced among host computers. In addition, VMotion enables hardware maintenance to be performed without service interruption by migrating a work load off a host computer that needs to be shut down.

When a VM connected to a PAN is moved to a destination host that has not implemented the PAN, the destination host and the VSwitch in the destination host need to add support for the PAN that the VM is using. This means, among other things, obtaining or creating the addressing mode table in the destination host. If the VM moves to a host outside the physical network connected to the source host, then encapsulation may be needed to reach the VM after the migration, and the functions in the addressing mode tables are adjusted accordingly. Additionally, in the case where the VM moves to a host outside the physical network where the source host resides, the addressing mode tables in other hosts implementing the PAN need to be updated to reflect the new location of the migrating VM. Further yet, if the migrating VM was the last VM for the PAN in the source host, then there is no VM left connected to that PAN in the source host and the multicast group for that PAN on that host can be terminated after the migration.

Referring now to the scenario of FIG. 8, VM N is migrating from host 802 to host 806. VM N is connected to PAN N3 in VSwitch 804. Host 806 does not have support for PAN N3 before VM N's migration. In one embodiment, VSwitch 808 adds functionality for PAN N3 before migrating VM N. This means reserving ports in VSwitch 808 for PAN N3 and creating the addressing mode table for PAN N3. The addressing mode table can be obtained from the Virtual Infrastructure controller or from other host, such as source host 802. The rest of the process for migrating VM N is performed as usual, and VM N is connected to PAN N3 via VSwitch 808. For VM N, the migration is transparent and the layer 2 and layer 3 addresses for VM N have not changed during the migration, because the layer 2 address is still the internal layer 2 address for VM N, and the IP address of VM N has not changed.

In one embodiment, the Virtual Infrastructure Controller has policies for the migration of VMs from one host to another. The policies may be defined to save energy, increase processing bandwidth, improve resource availability, move VMs closer to the user, etc. The policies assess the costs and benefits associated with a potential move and a decision is made whether to migrate a VM or not. One of such policies relates to the goal of having VMs connected to the same PAN execute in as few hosts as possible. This improves communication speed within the PAN as many packets will end in the same host or in a host nearby. Additionally, the processing required is reduced as most packets may not have to be changed or only require address translation. Another benefit is that overall there will be fewer addressing modes tables in the virtual infrastructure as hosts, in general, will have to support a fewer number of PANs.

FIGS. 9A-9B illustrate the implementation of PANs in multiple layers, according to one embodiment. The concept of PANs implemented on top of physical networks can be expanded to define PANs implemented on top of other PANs, thereby forming a stack of PAN layers. This means, that a private network can be defined to be implemented on top of another private network. In one embodiment, this is implemented as a VSwitch that connects to another VSwitch instead of connecting to a physical network. In another embodiment, the VSwitch is aware of the different layers and performs all the required functions to send packets out of the host into the physical network. For example, the VSwitch would first use an addressing mode table for the top layer PAN to obtain a first modified packet. Then, the VSwitch would use the second addressing mode table from the second PAN on the modified packet, to obtain a new packet to send down the stack until the final packet is sent on the physical network. This process is described in FIG. 9A, where there are N layers or network overlays. At each level, the packet suffers a potential transformation as previously described, and then the packet is handed to the next layer until the packet reaches the Physical NIC.

In another embodiment, instructions are obtained at each layer and the last layer would do the actual packet modification, including the required translations, encapsulations, etc. In yet another embodiment, as shown in FIG. 9B, the multiple layers are consolidated into two logical layers, the top network overlay interfacing with the VM and the bottom network overlay interfacing with the Physical NIC. The packet modification tasks are done at the top overlay, or the bottom overlay, or the tasks are split between the top and the bottom network overlay. Further, in one more embodiment, a single network overlay layer (not shown) is used that performs all the tasks required for each and every network overlay.

FIG. 10 shows the process flow for implementing private allocated networks in a virtual infrastructure in accordance with one embodiment of the invention. In operation 1002, a plurality of virtual switches are created in one or more hosts in the virtual infrastructure, where each port in the plurality of virtual switches is associated with a private allocated network (PAN) from a plurality of PANs. See for example, FIGS. 3-6 where virtual switches are created in each of the hosts. Intranet traffic within each PAN is not visible to nodes that are not connected to the each PAN.

Further, in operation 1004 the method defines addressing mode tables for the intranet traffic within each PAN, where an entry in the addressing mode tables defines an addressing function for routing the intranet traffic between the virtual switches. Different types of addressing functions are supported by the virtual switches, as seen for example in the embodiments of FIGS. 7A-7B.

FIG. 11 is a simplified schematic diagram of a computer system for implementing embodiments of the present invention. It should be appreciated that embodiments of the invention described herein may be performed with a digital processing system, such as a conventional, general-purpose computer system. Special purpose computers, which are designed or programmed to perform only one function may be used in the alternative. As shown in FIG. 11, the computer system includes a central processing unit 1104, which is coupled through bus 1110 to random access memory (RAM) 1106, read-only memory (ROM) 1112, and mass storage device 1114. Program 1108 resides in RAM 1106, but can also reside in mass storage 1114. Program 1108 can include a virtual machine, a virtual router, and other programs used to implement embodiments of the invention. Mass storage device 1114 represents a persistent data storage device such as a floppy disc drive or a fixed disc drive, which may be local or remote. Network interface 1130 provides connections via network 1132, allowing communications with other devices. It should be appreciated that Central Processing Unit (CPU) 1104 may be embodied in a general-purpose processor, a special purpose processor, or a specially programmed logic device. Input/Output (I/O) interface provides communication with different peripherals and is connected with CPU 1104, RAM 1106, ROM 1112, and mass storage device 1114, through bus 1110. Sample peripherals include display 1118, keyboard 1122, cursor control 1124, removable media device 1134, etc.

Display 1118 is configured to display the user interfaces described herein. Keyboard 1122, cursor control 1124, removable media device 1134, and other peripherals are coupled to I/O interface 1120 in order to communicate information in command selections to CPU 1104. It should be appreciated that data to and from external devices may be communicated through I/O interface 1120.

Embodiments of the present invention may be practiced with various computer system configurations including hand-held devices, microprocessor systems, microprocessor-based or programmable consumer electronics, minicomputers, mainframe computers and the like. The invention can also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a network.

With the above embodiments in mind, it should be understood that the invention can employ various computer-implemented operations involving data stored in computer systems. These operations are those requiring physical manipulation of physical quantities. Any of the operations described herein that form part of the invention are useful machine operations. The invention also relates to a device or an apparatus for performing these operations. The apparatus may be specially constructed for the required purpose, such as a special purpose computer. When defined as a special purpose computer, the computer can also perform other processing, program execution or routines that are not part of the special purpose, while still being capable of operating for the special purpose. Alternatively, the operations may be processed by a general purpose computer selectively activated or configured by one or more computer programs stored in the computer memory, cache, or obtained over a network. When data is obtained over a network the data maybe processed by other computers on the network, e.g., a cloud of computing resources.

The embodiments of the present invention can also be defined as a machine that transforms data from one state to another state. The transformed data can be saved to storage and then manipulated by a processor. The processor thus transforms the data from one thing to another. Still further, the methods can be processed by one or more machines or processors that can be connected over a network. The machines can also be virtualized to provide physical access to storage and processing power to one or more users, servers, or clients. Thus, the virtualized system should be considered a machine that can operate as one or more general purpose machines or be configured as a special purpose machine. Each machine, or virtual representation of a machine, can transform data from one state or thing to another, and can also process data, save data to storage, display the result, or communicate the result to another machine.

The invention can also be embodied as computer readable code on a computer readable medium. The computer readable medium is any data storage device that can store data, which can be thereafter be read by a computer system. Examples of the computer readable medium include hard drives, network attached storage (NAS), read-only memory, random-access memory, CD-ROMs, CD-Rs, CD-RWs, magnetic tapes and other optical and non-optical data storage devices. The computer readable medium can include computer readable tangible medium distributed over a network-coupled computer system so that the computer readable code is stored and executed in a distributed fashion.

Although the method operations were described in a specific order, it should be understood that other housekeeping operations may be performed in between operations, or operations may be adjusted so that they occur at slightly different times, or may be distributed in a system which allows the occurrence of the processing operations at various intervals associated with the processing, as long as the processing of the overlay operations are performed in the desired way.

Although the foregoing invention has been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications can be practiced within the scope of the appended claims. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims. 

1-23. (canceled)
 24. A method of implementing private networks over a shared physical network, the method comprising: configuring a first set of software forwarding elements executing on a first set of host computers to implement a first private network over the physical network for a first tenant; configuring a second set of software forwarding elements executing on a second set of host computers to implement a second private network over the physical network for a second tenant; the first and second sets of host computers having at least one particular host computer in common on which a particular software forwarding element executes, and configuring the first and second sets of forwarding elements comprises configuring a first port of the particular software forwarding element to be part of the first private network, and configuring a second port of the particular software forwarding element to be part of the second private network.
 25. The method of claim 24 further comprising configuring the first and second sets of forwarding elements comprises configuring the particular software forwarding element to use first and second addressing tables respectively for first and second private networks to determine how to forward packets received at the first and second ports.
 26. The method of claim 24 further comprising configuring the first and second sets of forwarding elements comprising configuring the particular software forwarding element to use first and second sets of addresses that are internal to the respective first and second PANs and to use a third set of addresses that are external to the first and second PANs and are for the shared physical network.
 27. The method of claim 26, wherein the first and second sets of addresses comprise internal MAC (media access control) addresses while the third set of addresses comprise external MAC addresses.
 28. The method of claim 26, wherein at least one address is in both the first and second sets of addresses as the first and second PANs use overlapping address spaces.
 29. The method of claim 26, wherein configuring the first set of forwarding elements comprises configuring the particular forwarding element to: receiving a first packet, from a first machine executing on the particular host computer, that has a destination address to a destination in the first private network; make a forwarding decision for the first packet based on the destination address in the first private network; encapsulate the first packet using a second destination address in the physical network; and transmit the encapsulated first packet to the physical network that processes the first packet using the second destination address.
 30. The method of claim 29, wherein the machine is a virtual machine executing on the particular host computer.
 31. The method of claim 29, wherein configuring the second set of forwarding elements comprises further configuring the particular forwarding element to: receiving a second packet, from a second machine executing on the particular host computer, that has a destination address to a destination in the second private network; make a forwarding decision for the second packet based on the destination address in the second private network; encapsulating the second packet using a second destination address in the physical network; and transmitting the encapsulated second packet to the physical network that processes the second packet using the second destination address.
 32. The method of claim 31, wherein the destination addresses of the first and second packets that are in the first and second private networks are the same address.
 33. The method of claim 29, wherein the second destination address is an address of a host computer that hosts a machine having the destination address in the physical network.
 34. A non-transitory machine readable medium storing a program which when executed by at least one processing unit implements private networks over a shared physical network, the program comprising sets of instructions for: configuring a first set of software forwarding elements executing on a first set of host computers to implement a first private network over the physical network for a first tenant; configuring a second set of software forwarding elements executing on a second set of host computers to implement a second private network over the physical network for a second tenant; the first and second sets of host computers having at least one particular host computer in common on which a particular software forwarding element executes, and the sets of instructions for configuring the first and second sets of forwarding elements comprises sets of instructions for configuring a first port of the particular software forwarding element to be part of the first private network, and configuring a second port of the particular software forwarding element to be part of the second private network.
 35. The non-transitory machine readable medium of claim 34, wherein the sets of instructions for configuring the first and second sets of forwarding elements further comprises sets of instructions for configuring the particular software forwarding element to use first and second addressing tables respectively for first and second private networks to determine how to forward packets received at the first and second ports.
 36. The non-transitory machine readable medium of claim 34, wherein the sets of instructions for configuring the first and second sets of forwarding elements further comprises sets of instructions for configuring the particular software forwarding element to use first and second sets of addresses that are internal to the respective first and second PANs and to use a third set of addresses that are external to the first and second PANs and are for the shared physical network.
 37. The non-transitory machine readable medium of claim 36, wherein the first and second sets of addresses comprise internal MAC (media access control) addresses while the third set of addresses comprise external MAC addresses.
 38. The non-transitory machine readable medium of claim 36, wherein at least one address is in both the first and second sets of addresses as the first and second PANs use overlapping address spaces.
 39. The non-transitory machine readable medium of claim 36, wherein the set of instructions for configuring the first set of forwarding elements comprises a set of instructions for configuring the particular forwarding element to: receive a first packet, from a first machine executing on the particular host computer, that has a destination address to a destination in the first private network; make a forwarding decision for the first packet based on the destination address in the first private network; encapsulate the first packet using a second destination address in the physical network; and transmit the encapsulated first packet to the physical network that processes the first packet using the second destination address.
 40. The non-transitory machine readable medium of claim 39, wherein the machine is a virtual machine executing on the particular host computer.
 41. The non-transitory machine readable medium of claim 39, wherein the set of instructions for configuring the second set of forwarding elements further comprises a set of instructions for configuring the particular forwarding element to: receive a second packet, from a second machine executing on the particular host computer, that has a destination address to a destination in the second private network; make a forwarding decision for the second packet based on the destination address in the second private network; encapsulate the second packet using a second destination address in the physical network; and transmit the encapsulated second packet to the physical network that processes the second packet using the second destination address.
 42. The non-transitory machine readable medium of claim 41, wherein the destination addresses of the first and second packets that are in the first and second private networks are the same address.
 43. The non-transitory machine readable medium of claim 39, wherein the second destination address is an address of a host computer that hosts a machine having the destination address in the physical network. 